These are especially materials and/or compounds thereof whose oligodynamical effect is known, such as silver, copper and gold, but also other heavy metals such as zinc and also lanthanides that have an effect on bacteria and/or fungi as desired according to this invention, i.e. they eliminate them, they prevent them from multiplying as well as from sticking to or embedding themselves in the plastic, or at least largely keep them from doing so.
A look at the present situation on the market shows that pre-products or finished parts made of such plastics are not yet commercially available, but according to the state of the art they can indeed be produced to function.
One reason why these products have not yet been introduced on the market to a considerable extent, is most likely the question of time and/or energy and thus costs involved in the production of such plastics.
On the one hand, this holds true for the costs of the amounts of metal and/or metal compound necessary for the desired purpose, in particular of silver, when these substances are to be included in the plastic in the powder form, in which case the lower limit for the metal and/or metal compound to be effective is frequently stated to be in an order of magnitude of 1 wt. % of the plastic; however, larger amounts are always stated to be even more effective. In this context, reference is made to the patent publications U.S. Pat. No. 4,054,139, WO-A-84/01721, EP-A-0 190 504, DE-A-37 25 728, EP-A-0 251 783 and DE-A-39 42 112.
On the other hand, this holds true for the costs of the actually rather elaborate wet process for the treatment of plastics, e.g. according to DE-C-42 26 810, which correspondingly is only to be used in special cases and in which very small amounts of the active agent are sufficient.
Another way of avoiding the high material costs for antimicrobial finishing is not to subject the plastic as a whole to antimicrobial finishing but to coat the finished objects produced from this plastic with active agents.
However, all physical methods (such as vapor deposition, cathodic sputtering, plasma-assisted vapor deposition, ionic plating, ion implantation) and also the chemical methods (e.g. currentless electro-plating, reactive vapor deposition, reactive cathodic sputtering, CVD, PACVD) work such that only the surfaces facing the source of the active substance to be applied or, e.g. in the case of plasma-assisted methods, at least only the surfaces openly facing the environment are coated. The internal surfaces of objects, which are usually particularly important for medical applications, e.g. the internal surfaces of catheters, however, cannot be reached by the aforementioned methods and thus remain uncoated.